Motorized tape measure

ABSTRACT

Various aspects of tape measures with one or more of a sensor, a motor, and a clutch, are shown. The sensors described herein detect, through various mechanisms, the position of the retraction system of a tape measure. The measurements by the sensors may be used to control a motor to adjust an amount of tension in the spiral spring of a tape measure. In various embodiments a motor interacts with the retraction system of the tape measure via a clutch, which moderates an amount of force that the motor can communicate to the retraction system.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

The present application is a continuation of International PatentApplication No. PCT/US2020/037247, filed Jun. 11, 2020, which claims thebenefit of and priority to U.S. Provisional Application No. 62/861,710,filed Jun. 14, 2019, which are incorporated herein by reference in theirentireties.

BACKGROUND OF THE INVENTION

The present disclosure relates generally to the field of tape measures.The present disclosure relates specifically to a tape measure with botha retraction spring and a retraction motor and a sensor providinginformation to a controller/control system regarding operation of theretraction system (e.g., spring torque, retraction speed, etc.).

Tape measures are measurement tools used for a variety of measurementapplications, including in the building and construction trades. Sometape measures include a graduated, marked blade wound on a reel and alsoinclude a retraction system for automatically retracting the blade ontothe reel. In some tape measure designs, the retraction system is drivenby a coil or spiral spring that is tensioned, storing energy as the tapeis extended, and that releases energy to spin the reel, winding theblade back onto the reel.

SUMMARY OF THE INVENTION

One embodiment of the disclosure relates to a tape measure including ahousing, a tape reel rotatably mounted within the housing, a rotationalaxis defined by the tape reel around which the tape reel rotates, anelongate tape blade wound around the tape reel, a spiral spring coupledto the tape reel, a detector made of a second material that iselectrically-conductive, and a sensor that measures a capacitance of thedetector. When the elongate tape blade is unwound from the tape reel toextend from the housing the spiral spring stores energy, and the spiralspring releasing energy drives rewinding of the elongate tape blade onto the tape reel. The spiral spring is made of a first material that iselectrically-conductive.

Another embodiment of the disclosure relates to a tape measure includinga housing, a tape reel rotatably mounted within the housing, arotational axis defined by the tape reel around which the tape reelrotates, an elongate tape blade wound around the tape reel, a spiralspring located within the housing, a magnet that emits a magnetic field,and a detector that measures a change in the magnetic field caused by arepositioning of the spiral spring in response to a portion of the tapeblade being extended from or retrieved into the housing. When theelongate tape blade is unwound from the tape reel to extend from thehousing the spiral spring stores energy, and the spiral spring releasingenergy drives rewinding of the elongate tape blade on to the tape reel.The spiral spring is made of a first material that iselectrically-conductive.

Another embodiment of the disclosure relates to a tape measure includinga housing defining an interior surface, a tape reel rotatably mountedwithin the housing, a rotational axis defined by the tape reel aroundwhich the tape reel rotates, an elongate tape blade wound around thetape reel, a spiral spring located within the housing, an axle rotatablymounted within the housing, the axle defining a first end and anopposing second end, a motor shaft rotatably mounted within the housing,the motor shaft defining a first end and an opposing second end, thefirst end of the motor shaft interfacing with the first end of the axle,and a sensor that measures a position of the second end of the motorshaft. When the elongate tape blade is unwound from the tape reel toextend from the housing the spiral spring stores energy, and the spiralspring releasing energy drives rewinding of the elongate tape blade onto the tape reel.

Another embodiment of the disclosure relates to a motorized tape measurewith a sensor. The sensor measures an aspect of the tape measure, suchas the speed at which the tape blade is being extracted out of orretrieved into the housing, an amount that the tape blade is still inthe housing, and/or an estimated amount of tension being exerted by theretraction system. Based on these measurements, the motor exerts a forceon the tape spool. For example, the motor may exert a counter-force onthe retraction system, thus moderating the speed at which the tape bladeis retrieved into the housing.

According to one embodiment, a tape measure includes a sensor, ahousing, an arbor that rotates within the housing, a tape reel thatrotates within the housing, an elongate tape blade wound around the tapereel, a retraction system for the elongate tape blade, a hook assemblycoupled to an outer end of the elongate tape blade, a spiral spring, anda motor that interfaces with the retraction system. When the elongatetape blade is unwound from the tape reel to extend from the housing, thespiral spring stores energy, and the spiral spring releasing energydrives rewinding of the elongate tape blade on to the tape reel. Thesensor measures an aspect of the tape measure and generates a controlsignal. The motor receives the control signal and interfaces with theretraction system based on the control signal.

In more specific embodiments, the motor interfaces with the tape spoolvia a clutch, such as a detent clutch or a slip clutch. The clutchprovides an upper limit on the amount of tension in the retractionsystem, so when the maximum amount of tension is exceeded the clutchslips to prevent a further increase to the tension. The clutch includesan adjustment mechanism that permits a user to control the maximumamount of tension that the clutch can receive before slipping.

In another specific embodiment, the tape measure includes a circuitboard and a position sensor. The position sensor measures thepositioning of the spring, such as by detecting the proximity of thespring to one or more sensing locations of the position sensor. In oneexample, the position sensor includes a series of concentric circles ofvarying diameters from an axis around which the spring is centered. Thedifferent concentric circles measure the amount (e.g., magneticinterference, density, mass) of the spring in proximity to therespective circle. Based at least in part on those measurements, thecircuit board generates a control signal for the motor to interface withthe retraction system. In one specific embodiment, the position sensoris one or more metal detectors.

In another specific embodiment, the tape measure further includes atorque switch. The torque switch includes an arbor spacer coupled to thearbor, and a motor shaft spacer coupled to the motor. The arbor spacerand the motor shaft spacer are circumferentially biased away from eachother by one or more biasing elements. The orientation of the arborspacer and the motor shaft spacer changes in response to the tension inthe tape measure's retraction system. The change in the relativeorientation of the components of the torque switch is measured, andbased on that measurement a control signal for the motor is generated.

In another specific embodiment, the motor includes a shaft that isaxially aligned with the arbor. The motor shaft and the arbor interfaceat a cammed interface. The arbor and the motor shaft define a collectivelength, which changes in response to the arbor and the motor shaftrotating with respect to each other. The tape measure further includes abiasing element that exerts a biasing force compressing the arbor andmotor shaft together. A distance between the motor shaft and the housingis measured, and based on that measurement a control signal for themotor is generated.

In another specific embodiment, the elongate blade includes a series ofmarkings arranged along the length of the elongate blade. In anotherspecific embodiment, a rotating component in the tape measure, such asthe tape spool, includes a series of markings that are radially arrangedaround a central axis. The sensor monitors the series of markings todetermine a status of the tape measure. In various uses, the sensormonitors the speed that the markings are moving, and/or monitors a totaldisplacement of the elongate blade (e.g., by counting the total numberof markings that have moved past a sensor).

Additional features and advantages will be set forth in the detaileddescription which follows, and, in part, will be readily apparent tothose skilled in the art from the description or recognized bypracticing the embodiments as described in the written description andclaims hereof, as well as the appended drawings. It is to be understoodthat both the foregoing general description and the following detaileddescription are exemplary.

The accompanying drawings are included to provide further understandingand are incorporated in and constitute a part of this specification. Thedrawings illustrate one or more embodiments and, together with thedescription, serve to explain principles and operation of the variousembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a tape measure with a motor and clutch,according to an exemplary embodiment.

FIG. 2 is a detailed view of a portion of the tape measure depicted inFIG. 1.

FIG. 3 is a schematic view of a tape measure, according to anembodiment.

FIG. 4 is a schematic view of a tape measure, according to anembodiment.

FIG. 5 is a schematic view of a tape measure, according to anembodiment.

FIG. 6 is an exploded view of a tape measure, according to anembodiment.

FIG. 7 is a detailed view of a portion of the tape measure of FIG. 6.

FIG. 8 is an exploded view of a tape measure, according to anembodiment.

FIG. 9 is a detailed view of a portion of the tape measure of FIG. 8.

FIG. 10 is a schematic view of a tape measure, according to anembodiment.

FIG. 11 is an exploded view of the tape measure of FIG. 10.

FIG. 12 is a detailed view of a portion of the tape measure of FIG. 10.

FIG. 13 is a detailed view of the portion of the tape measure depictedin FIG. 12, shown in a different configuration.

FIG. 14 is an exploded view of a tape measure, according to anembodiment.

FIG. 15 is a schematic view of a portion of the tape measure of FIG. 14.

FIG. 16 is a detailed view of the portion of the tape measure depictedin FIG. 15, shown in a different configuration.

FIG. 17 is a perspective view of a tape measure, according to anembodiment.

FIG. 18 is a perspective view of the tape measure of FIG. 17, accordingto an embodiment.

FIG. 19 is a schematic view of the tape measure of FIG. 18, according toan embodiment.

FIG. 20 is an exploded view of a tape measure, according to anembodiment.

FIG. 21 is a detailed view of a portion of the tape measure of FIG. 20,according to an embodiment.

FIG. 22 is a detailed view of a portion of the tape measure of FIG. 20,according to an embodiment.

FIG. 23 is a detailed view of a portion of the tape measure of FIG. 20,according to an embodiment.

FIG. 24 is an exploded view of a tape measure, according to anembodiment.

DETAILED DESCRIPTION

Referring generally to the figures, various embodiments of a tapemeasure are shown. Various embodiments of the tape measure discussedherein include an innovative retraction system that includes a motor andsensor(s) that generate control signals for the motor. Some tape measureblades are susceptible to damage/breakage due to high speed duringretraction. For example, high speeds during retraction may cause thetape blade to whip (e.g., the tendency of the tape measure blade to bendor snap back on itself during fast retraction), which can crack or tearthe tape blade, and similarly, high retraction speeds can damage thetape blade when the tape hook contacts the tape housing at the end ofretraction. Applicant believes that the tape measure retraction systemdescribed herein provides for retraction speed control that can limitsuch sources of tape measure damage while at the same time providing amore compact tape measure without sacrificing tape length or retractionperformance.

As will generally be understood, in certain tape measure designs, aspring stores energy during tape blade extension and applies aforce/torque to a reel causing the tape blade to wind on to the reelduring tape blade retraction. Various aspects of spring design, such asspring energy, torque profile, spring constant, etc., are selected toensure that operation of the spring has enough energy to providesatisfactory tape retraction. However, because of the physics andcharacteristics of the typical tape measure spiral spring, in order toensure full tape retraction at a satisfactory speed, the typical tapemeasure spiral spring delivers excess energy to the tape blade duringretraction, which in turn translates into undesirably highly retractionspeeds and whip, particularly toward the end of retraction. In addition,for a given spiral spring design increasing spring energy to provide forretraction of longer, wider and/or thicker measuring tape bladestypically requires use of a larger spiral spring, which in turn resultsin a larger tape measure.

As discussed herein, Applicant has developed various innovative tapemeasure blade retraction systems that provide a desired level of springenergy while utilizing a relatively short or small volume spring, whilemaintaining a relatively small tape measure housing (e.g., a tapemeasure outer diameter) and/or while providing desired retractioncharacteristics. As discussed in more detail, the tape retraction systemdiscussed herein utilizes a motor that interfaces with the retractionsystem based on measurements performed by sensors. The sensors monitorthe current state of the tape measure (e.g., the amount of torquecurrently being exerted by the spiral spring) and the changing state ofthe tape measure (e.g., the speed at which the tape blade is beingextracted from or retrieved into the housing). Based on thisinformation, the tape retraction system adjusts the tension in thespring to moderate the retraction speed of the tape blade, thus reducingthe chances of the tape blade whipping or high retraction speedsdamaging the tape blade when tape hook encounters the housing at the endof retraction.

In various embodiments, the tape retraction system includes a clutchbetween the motor and the tape reel around which the tape blade iswrapped. The clutch limits and/or prevents the motor from over-torqueingthe tape reel by limiting an amount of tension in the spiral spring.

Turning to FIGS. 1-2, various aspects of a tape measure, shown as tapemeasure 10, are shown. In FIGS. 1-2 tape measure 10 includes a housing12, a sensor, a tape reel 14, an elongate tape blade 20, a hook assemblycoupled to an end of the elongate tape blade 20, a spiral spring 16, anda motor.

A motor in tape measure 10 interfaces with the retraction system of thetape measure 10 based at least in part on a signal generated by asensor. The tape blade 20 is wound around the tape reel 14, which isrotatably coupled to the housing, rotating about axis 8 with respect tohousing 12. The spiral spring 16 is coupled to the tape reel 14 suchthat the spiral spring 16 stores energy when the elongate tape blade 20is unwound from the tape reel to extend from the housing, and the spiralspring 16 releasing energy drives rewinding of the elongate tape blade20 on to the tape reel 14. In general, the tape blade 20 is an elongatedstrip of material including a plurality of graduated measurementmarkings, and in specific embodiments, the tape blade 20 is an elongatedstrip of metal material (e.g., steel material) that includes an outermost end coupled to a hook assembly. The tape blade 20 may includevarious coatings (e.g., polymer coating layers) to help protect the tapeblade 20 and/or the graduated markings of the blade from wear, breakage,etc.

The tape measure 10 includes a retraction system that includes a spring,such as a spiral spring 16. In general, the spiral spring 16 is coupledbetween an arbor 18 and a tape reel 14 (or through the tape reel 14 todirectly couple to an inner end of the elongate tape blade) such thatthe spiral spring 16 is coiled or wound to store energy during extensionof the tape from the housing 12 and is unwound, releasing energy,driving rewinding of the tape blade 20 onto the tape reel 14 duringretraction of the tape blade 20 (e.g., following release or unlocking ofthe tape blade 20). Specifically, when the tape blade 20 is unlocked orreleased, the spring 16 expands, driving the tape reel 14 to wind up thetape blade 20 and to pull the tape blade 20 back into the housing 12.

Turning to FIGS. 3-5, schematics of various tape measures in shown.Turning to FIG. 3, tape measure 30 includes a motor 22 that interfaceswith a tape reel 14 that is coupled to a tape blade 20. A sensor 24monitors the status of the tape reel 14, such as a position of and/or anamount of tension being stored by the spiral spring 16. In oneembodiment, a static state of tape measure is measured by sensor 24,such as the torque exerted by the spiral spring at a given time.Alternatively, a moving component of tape measure is measured, such asthe speed at which the elongate tape blade is being extracted from orretrieved into the tape measure housing. Based on measurements by thesensor 24, the motor 22 is controlled to adjust the tension in thespiral spring coupled to the tape reel 14.

Turning to FIG. 4, in specific embodiments, tape measure 40 the motor 22interfaces with tape reel 14 via a clutch 26. The clutch 26 limitsand/or prevents the motor 22 from providing an excessive amount oftension into the spiral spring coupled to the tape reel 14. Similar toFIG. 3, the sensor 24 monitors the status of the tape reel 14, such asan amount of tension being stored by the spiral spring.

Turning to FIG. 5 in specific embodiments, tape measure 50 the motor 22interfaces with the tape reel 14 via a clutch 26. The clutch 26 limitsand/or prevents the motor 22 from providing an excessive amount oftension into the spiral spring coupled to the tape reel 14. Similar toFIG. 3, the sensor 24 monitors the status of the tape reel 14, such asan amount of tension being stored by the spiral spring. Based onmeasurements by the sensor 24, the motor 22 is controlled to adjust thetension in the spiral spring coupled to the tape reel 14.

Turning to FIGS. 6-24, various aspects of sensors and clutches for tapemeasures are provided. FIGS. 6-19 depict various aspects of sensors thatare used in tape measures, and FIGS. 20-24 depict various aspects ofclutches that are used in motorized tape measures between the motor andthe tape reel. It is contemplated herein that any of the sensorsdescribed herein may be used with any of the clutches described herein,consistent with the schematic depiction of tape measure 50 depicted inFIG. 5.

Turning to FIGS. 6-7, various aspects of a sensor for tape measure 110are shown. Tape measure 110 is similar to tape measure 10, 30, 40, and50, except for the differences described herein. Tape measure 110includes a sensor, shown as capacitive sensor 112, that interacts withantennas 114, 120 and 126 to detect torque and/or position of spiralspring 16. Spiral spring 16 is coupled to tape reel 14 and stores energyas the tape blade 20 is retrieved from tape measure 110.

In a specific embodiment, sensor 112 measures a capacitance of one ormore of first antenna 114, second antenna 120 and third antenna 126.Antenna 114, 120 and 126 are arranged on a platform, shown as a circuitboard. Based on the capacitance measurement(s), sensor 112 determineswhether to send a signal to adjust an amount of tension in spiral spring16.

The sensor 112 can detect the spooling or unspooling of the spring 16 bydetecting whether the mass of the spring 16 is near the arbor 18, nearthe peripheral wall of the tape reel 14, or in-between. In a specificembodiment, antennas 114, 120 and 126 are formed of anelectrically-conductive material, and spring 16 is formed of anelectrically-conductive metal, such as steel. Sensors 112 measure anelectrical capacitance of one or more of antennas 114, 120 and 126 withrespect to spring 16 based on a measurement of an amount of spring 16proximate the respective antenna 114, 120 and 126. For example, when thespring 16 is wound relatively tightly around the arbor 18, the innermostantenna 114 can detect this position (e.g., by comparing a threshold tothe capacitance of the innermost antenna 114 and the spring 16).Similarly, the outermost antenna 126 can detect that the spring 16 isunwound and much of the mass of the spring 16 is near the interior wall28 of the tape reel 20.

In a specific embodiment, sensor 112 generates a first signal based on ameasurement of the electrical capacitance of antenna 114, generates asecond signal based on a measurement of the electrical capacitance ofantenna 120, and generates a third signal based on a measurement of theelectrical capacitance of antenna 126. In another embodiment, sensor 112generates a first signal based on measurements of the electricalcapacitance of one or more of antenna 114, antenna 120, and antenna 126.

Turning to FIG. 7, various radii of antennas 114, 120 and 126 withrespect to rotational axis 8 are shown. In a specific embodiment,antennas 114, 120 and 126 extend circumferentially around axis 8 and arearranged in concentric circles around rotational axis 8. With respect torotational axis 8, outermost antenna 126 has an inner radius 128 and anouter radius 130, central antenna 120 has an inner radius 122 and anouter radius 124, and innermost antenna 114 has an outer radius 116 andan inner radius that has a distance of zero (0), because innermostantenna 114 is positioned on rotational axis 8.

Any number of antennas 114, 120 and 126 can be used to provide anysuitable level of resolution of detection. Similarly, an analog outputmay also be used by comparing capacitance of various antennas (e.g.,compare the capacitance of the inner most conductive ring to theoutermost conductive ring). In various embodiments, the antennas can beinductive sensor coils that change inductance relative to the positionof the spiral spring 16. The resolution of inductance measurement(s) canprovide a digital response (e.g., above a certain threshold vs below),or it can provide a very fine measurement (e.g., similar to an analogsignal).

In a specific embodiment, antennas 114, 120 and 126 are arrangedsymmetrically around the rotational axis 8 of the spring 16 (best-shownFIGS. 6-7). In another embodiment, the antennas are arrangedasymmetrically around the rotational axis 8 of the spring 16. In aspecific embodiment, a motor receives a signal from sensor 112 andadjust an amount of tension in spiral spring 16.

Turning to FIGS. 8-9, various aspects of tape measure 210 are shown.Tape measure 210 is similar to other tape measures described hereinexcept for the identified differences. One or more Hall-effect sensors(e.g., of copper), shown as detectors 214, 220 and 226, can be placed atvarious radii 218, 224 and 230 from the center of the arbor 18 to detectthe mass of the spring 16. For example, one or more of detectors 214,220 and 226 may measure a change in the magnetic field caused by arepositioning of the spiral spring 16 in response to the tape blade 20being extended from or retrieved into the housing 12. In anotherembodiment, one or more of detectors 214, 220 and 226 measure a strengthand/or an orientation of magnetic fields passing through that respectivedetector 214, 220 and 226. The sensor 212, such as a circuit board,receives the measurements from the plurality of detectors 214, 220 and226 and based on those measurements estimates the extent to which thespring 16 is wound or unwound (e.g., the extent to which the mass ofspring 16 is centered near its rotational axis 8 or the extent to whichthe spring 16 is expanded away from its rotational axis 8).

In a specific embodiment, detectors 214, 220 and 226 and magnets 216,222 and 228 are positioned at various radii 218, 224, and 230 aroundaxis 8. Magnets 216, 222 and 228 each produce a magnetic field that isdetected by detectors 214, 220 and 226. Spring 16 affects the magneticfields produced by magnets 216, 222 and 228 such that as spring 16adjusts position (e.g., when tape blade is spooled or unspooled), thestrength and/or orientation of the magnetic fields changes. Detectors214, 220 and 226 measure the magnetic field(s) and/or the changes to themagnetic field(s) and generate one or more signals to sensor 212 basedon the measurements of the magnetic fields. Sensor 212 in turn generatesa first signal as a result of measuring the change in the magneticfield, the first signal indicating a configuration of the spiral spring16. In a specific embodiment, the detectors 214, 220 and 226 arearranged proximate one the magnets 216, 222 and 228 (e.g., the detectorsinterfaces against a magnet).

Referring to FIGS. 10-13, various aspects of device to measure torque,shown as torque switch 336, of spiral spring 16 in tape measure 310 areshown. Tape measure 310 is similar to the other tape measures describedherein except for the differences noted. Tape measure 310 includesanother way to detect torque in spiral spring 16 by detecting relativeposition of a motor shaft 326 and an arbor shaft 312 that are normallyspaced apart.

In FIG. 10, the motor shaft 326 is fixedly coupled to a motor shaftspacer 320 in such a way that the motor shaft 326 and the motor shaftspacer 320 do not move with respect to one another. Similarly, the arbor312 and the arbor spacer 314 are fixedly coupled together. Both thearbor spacer 314 and the motor shaft spacer 320 are positioned to rotatewith respect to the arbor 312. The arbor spacer 314 and the motor shaftspacer 320 both rotate around axis 8 but can rotate at slightlydifferent rates (e.g., in one embodiment one spacer can lag or lead theother as the two spin, but one cannot freely spin while the otherremains stationary; in another embodiment one can spin while the otherremains stationary).

The arbor spacer 314 and motor shaft spacer 320 are biased away fromeach other with respect to axis 8 by one or more biasing elements, shownas springs 328, 332. Springs 328, 332 are placed between the two spacers314, 320. As a torque is applied (e.g., by the motor shaft 320), theassembly rotates, but the relative position between the spacers 314, 320changes. For example, angle 330 and angle 334 between arbor spacer 314and motor spacer 320 change. Angle 330 is defined between end 316 ofarbor spacer 314 and end 322 of motor spacer 320. Angle 334 is definedbetween end 318 of arbor spacer 314 and end 324 of motor spacer 320.

The amount of change for angle 330 and angle 334 is dependent on theamount of torque applied and the strength of the springs 328, 332. Theangles 330, 334 between the spacers 314, 320 can be measured in ananalog manner (e.g., using a distance meter such as an optical sensor tomeasure the distance between two points on the spacers 314, 320; whenthe speed of the arbor shaft 312 or motor shaft 326 is known, measuringthe time it takes for the open portion to rotate through an opticalsensor) or in a discrete manner (e.g., placing a mechanical switchbetween the spacers 314, 320 that connects when a torque threshold isovercome).

When motor 338 receives a control signal to exert a force on the arbor312, the motor 338 generates a force against the motor shaft spacer 320.Motor shaft spacer 320 thereby exerts a force against the biasingelements, shown as springs 328, 332, which exert a force against thearbor spacer 314. Because the arbor spacer 314 is fixedly coupled to thearbor 312, which is coupled to the spring 16 of tape measure 310, thearbor spacer 314 and arbor 312 adjust position based on the interferingbiasing forces from the springs 328, 332 and the spring 16 of tapemeasure 310. As a result, the angles 330, 334 between the motor shaftspacer 320 and the arbor spacer 314 changes. The change of one or moreof angles 330, 334 (compare FIG. 12 to FIG. 13) is measured to estimatethe current torque exerted between the spiral spring 16 of tape measure310 spring and springs 328, 332. Based on these measurements a controlsignal is generated and the motor 338 selectively adjusts the force thatmotor 338 is indirectly exerting on the arbor 312 via the motor shaftspacer 320.

In another embodiment, torque on the spiral spring 16 can be determinedby measuring the input angle of the main spring and compare it to theoutput angle of the tape spool. The output is simply that of the tapespool 20. Once the two angles are known, the torque can be inferred viasoftware because the main spring 16 has an associated force with therelative angle.

Referring to FIGS. 14-16, various aspects of tape measure 410 are shown.Tape measure 410 is similar to the other tape measures described hereinexcept as noted. Torque of spring 16 coupled to tape reel 14 is measuredby monitoring a linear movement of one of the arbor 416 and motor shaft422. Between two sides of the housing 12 is an axle, shown as arbor 416,a secondary axle, shown as motor shaft 422, and a spring 430. Arbor 416extends from first end surface 418 to second end surface 420, and motorshaft 422 extends from first end surface 424 to second end surface 426.Second end surface 420 of arbor 416 and first end surface 424 of motorshaft 422 interface with each other. In a specific embodiment, secondend surface 420 of arbor 416 and first end 424 of motor shaft 422 areboth angled (best-shown FIGS. 15-16). As the motor shaft 422 and thearbor 416 rotate with respect to one another and interface against eachother, the total length of the arbor 416 and motor shaft 422 varies.

Sensor 432 monitors the length of arbor 416 and motor shaft 422, such asby monitoring distance 428 between second end 426 and the interiorsurface of housing 12. In a specific embodiment, sensor 432 generates afirst signal as a result of measuring the position of the second end 426of the motor shaft 422, the first signal indicating a configuration ofthe spiral spring 16.

The spring 430 presses motor shaft 422 towards arbor 416, therebybiasing the total length of the arbor 416 and motor shaft 422 to be asshort as possible when no torque is applied. As torque is applied, theforce spring 430 is overcome, and the angled surfaces rotate withrespect to one another, thereby causing the spring 430 to compress andthe distance 428 between motor shaft 422 and housing 12 to decrease. Thedistance 428 can be measured by sensor 432 analog or digitally.

In one embodiment, when the elongate tape blade 20 is fully retractedwithin the housing 12, spiral spring 16 of tape measure 410 is in alow/no torque state (best-shown in FIG. 15). In this position, theaxially-aligned spring 430 biases motor shaft 422 towards the arbor 416,and the distance 428 measured between the motor shaft 422 and housing 12is at its greatest. As the elongate tape blade 20 is extracted from thehousing 12, arbor 416 rotates. The arbor 416 interfaces with the motorshaft 422 via their respective angled surfaces to bias the motor shaft422 against spring 430. This reduces the distance 428 between the motorshaft 422 and inner surface 414 of housing 12. One or more sensorsmonitor this distance and based on the measurement(s) the system infersthe current positioning of the elongate tape blade 20 (e.g., fullyretracted within the housing 12, fully extended out of the housing 12,an intermediate state between fully retracted and fully extended). Thearbor 416 is configured to rotate less than 360 degrees with respect tothe motor shaft 422 to avoid resetting the distance 428 being measured.

It is contemplated herein that any aspect of the interface between motorshaft 422 and arbor 416 may be measured, such as an orientation of thearbor 416 with respect to the motor shaft 422, a distance between thearbor 416 and the housing 12 (if the arbor 416 is permitted tolongitudinally slide along its axis rather than the motor shaft 422).

Referring to FIGS. 17-19, various aspects of tape measure 510 are shown.Tape measure 510 is similar to the other tape measures described hereinexcept for the differences noted. Tape measure 510 monitors tension ofspiral spring 16 by monitoring the speed that tape blade 520 is movingand/or the amount of tape blade 20 that has been paid out or reeled in.Speed of the tape blade 520 can be determined by using an opticaldetector 530 that detects indicia, shown as markings 518, on a bottomsurface the tape blade 520 (e.g., an alternating white and black stripepattern).

Turning to FIG. 19, a schematic view of a portion of tape measure 510 isshown. In a specific embodiment, optical detector 530 is locatedproximate where tape blade 20 exits housing. From this position, opticaldetector 530 monitors the speed that tape blade 520 is moving pastoptical detector 530, and/or optical detector 530 monitors an amount oftape blade 520 that has moved past optical detector 530 to exit housing12 (e.g., by counting markings 518 that have moved past optical detector530).

In one embodiment, the elongate tape blade 520 is monitored to determinea speed at which the elongate tape blade 520 is being extracted from orretrieved into the housing 12. The retraction system determines thespeed at which the markings are moving past the sensor (e.g., bymeasuring an amount of time between when neighboring markings move pastthe sensor). Based on that determination, the tape retraction systemselectively modifies the tension in the spiral spring. For example, ifthe retraction speed is at or approaching a threshold speed, the taperetraction system interfaces with the spiral spring to reduce theretraction speed such as by reducing the tension in the spiral springthat biases the tape blade into the housing. In another example, theacceleration of the markings is measured and compared to a threshold.

In another embodiment, optical detector 530 counts the markings 518 asthey move past the optical detector 530 to determine the current stateof tape measure 510. In one embodiment, the markings 518 can alternatein frequency/distance such that the optical detector 530 can determinespeed as well as direction that tape blade 520 is moving past opticaldetector 530.

In another embodiment, a rotating component in tape measure 510, such astape reel 14, includes a series of radially-arranged markings that aremonitored by the sensor(s). The sensor identifies when each markingmoves past the sensor and based on that identification the retractionsystem determines how much of the tape blade spool is extracted from thetape measure housing. Based on that determination, the tape retractionsystem selectively modifies the tension in the spiral spring. It iscontemplated herein that any rotating component (e.g., the arbor, thespiral spring) may include or define radially-arranged markings.

In another embodiment, the rotational speed can be converted into alinear speed of the tape blade 520 by taking into consideration theamount of tape blade 520 that has already been paid out (e.g.,determining the outer radius of the tape blade 520 that is still coiledon the tape reel 14).

Other methods of speed detection include magnetic/Hall-effect sensors.One or more magnets can be placed on the tape reel, and one or moreHall-effect sensors can determine the number of rotations, the speed ofrotation, etc. of the tape reel. Another method includes a device thatoperates similar to a governor on an engine. As the device rotatesfaster, the spring-loaded arms are forced outward by centrifugal forces.The further out that the arms are, the faster that the device isspinning.

In one embodiment, the one or more sensors are rotated with respect tothe housing 12 (e.g., the sensor(s) are disposed on the tape reel). Thesensor(s) monitor radially-arranged markings, such as on the housing, todetermine the status (e.g., the torque) of tape measure 10. In anotherembodiment the sensor(s) monitor radially-arranged markings on anothercomponent that is rotating with respect to the housing (e.g., thesensor(s) are on the tape reel monitor markings on the arbor, whichrotates with respect to the tape reel as the tape blade is extractedfrom or retrieved into the housing).

Referring to FIGS. 20-23, various aspects of tape measure 610 are shown.Tape measure 610 is similar to the other tape measures described hereinexcept for the differences noted. Clutch 626 is between arbor 618 andmotor shaft 632 to manage an amount of tension in spring 16.

Clutch 626 includes torque moderating component, shown as wheels 622,that interface against plate 634. Plate 634 circumferentially definemultiple peaks 630 and valleys 628. In a specific embodiment peaks 630.At a position of no torque and/or low tension in spring 16, spring 636biases wheels 622 towards valleys 628. As tension is exerted on spring16 (e.g., as tape blade 20 is withdrawn from housing 12), torque onarbor 618 rotates with respect to plate 634, and as a result wheels 622circumferentially move with respect to plate 634 at least partially fromvalleys 628 to peaks 630.

Referring to FIG. 24, various aspects of tape measure 710 are shown thatincludes an innovative clutch 736. Referring to FIG. 24, amotorized/hybrid tape measure 710 includes an electric motor 22, clutch736 and a spiral spring 16. An electric motor 22 drives a worm drivesystem. The worm drive system converts the rotational movement of thedrive shaft into orthogonal rotational movement with a gear reduction.The worm drive gear reduction is optimized based on speed needed torotate the spring arbor, the voltage and speed of the motor, and thebrake force of the motor needed to maintain the spring arbor stationarywhen the motor is not powered, among other factors.

Between the worm drive system and the spring arbor is a clutch 736. Theclutch 736 can be a detent or slip clutch. Shown in this image is adetent clutch. The clutch 736 prevents the motor from over driving orover torqueing the spring arbor. The clutch plates are pressed togetherby the tensioner spring. The stronger the compressive force of thespring, the higher the torque limit before the clutch slips. The amountof force applied to the clutch plates can be adjusted via the clutchadjustment screw. Attached to the spring arbor is one end of the spring.The other end of the spring is attached to the blade spool, which can beco-axial to and surround the spring.

Still referring to FIG. 24, the motor is used to adjust the amount oftorque that the spring applies to the blade spool. As the user pulls outthe blade 20 from the housing 12, the spring 16 winds up and, if theuser continues to pull out the blade 20, the spring 16 winds to apre-set torque limit, and the motor is used to adjust the spring arborto unwind the spring such that the spring applies less than the pre-settoque limit. Similarly, once the user allows the blade to wind back upinto the housing, the spring unwinds to another pre-set torque limit,and the motor is used to adjust the spring arbor to wind the spring suchthat the spring can continue to apply enough torque to the blade spoolto completely reel the blade in. Accordingly, in such embodiments,torque is measured. Two options for measuring torque are (i) at the mainspring and (ii) between the motor and the arbor.

To perform these measurements, tape measure 10 may include one or moresensors to detect a state of tape measure 710. Based on measurement(s)from the one or more sensors, a control signal for the motor isgenerated.

The motor interfaces with the retraction system based at least in parton the control signal. For example, in FIG. 24 the motor interfaces withthe tape spool. However, it is contemplated herein that the motorinterfaces with any of one or more components in the retraction system(e.g., the tape spool, the elongate tape blade, the arbor).

In various embodiments, the clutch system described herein is used incombination with the one or more embodiments with sensors also describedherein.

In one embodiment, when the elongate tape blade is fully retractedwithin the housing, tape measure's spiral spring is in a low/no torquestate. In this position, the total distance of the arbor and motor shaftis at its shortest. As the elongate tape blade is extracted from thehousing, the arbor rotates with respect to the motor shaft and the totaldistance of the arbor and motor shaft increases. One or more sensorsmonitor the distance of motor shaft and arbor, and based on themeasurement(s) the system infers the current positioning of the elongatetape (e.g., fully retracted within the housing, fully extended out ofthe housing, an intermediate state between fully retracted and fullyextended).

In one embodiment, motor shaft is rotatably coupled to three rollers,which each interface within a valley (e.g., a recessed portion between apair of extended portions). It is contemplated herein that any number ofrollers and valleys may be used, including switching which axle iscoupled to the rollers and which axle includes the cammed surface.

It is contemplated herein that any aspect of the motor shaft and arborinterface may be measured, such as an orientation of the arbor withrespect to the motor shaft, a distance between the arbor and the housing(if the arbor is permitted to longitudinally slide along its axis ratherthan the motor shaft), and/or a distance between the housing and atleast one of the arbor or housing.

It should be understood that the figures illustrate the exemplaryembodiments in detail, and it should be understood that the presentapplication is not limited to the details or methodology set forth inthe description or illustrated in the figures. It should also beunderstood that the terminology is for description purposes only andshould not be regarded as limiting.

Further modifications and alternative embodiments of various aspects ofthe invention will be apparent to those skilled in the art in view ofthis description. Accordingly, this description is to be construed asillustrative only. The construction and arrangements, shown in thevarious exemplary embodiments, are illustrative only. Although only afew embodiments have been described in detail in this disclosure, manymodifications are possible (e.g., variations in sizes, dimensions,structures, shapes and proportions of the various elements, values ofparameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter described herein. Someelements shown as integrally formed may be constructed of multiple partsor elements, the position of elements may be reversed or otherwisevaried, and the nature or number of discrete elements or positions maybe altered or varied. The order or sequence of any process, logicalalgorithm, or method steps may be varied or re-sequenced according toalternative embodiments. Other substitutions, modifications, changes andomissions may also be made in the design, operating conditions andarrangement of the various exemplary embodiments without departing fromthe scope of the present invention.

Unless otherwise expressly stated, it is in no way intended that anymethod set forth herein be construed as requiring that its steps beperformed in a specific order. Accordingly, where a method claim doesnot actually recite an order to be followed by its steps or it is nototherwise specifically stated in the claims or descriptions that thesteps are to be limited to a specific order, it is in no way intendedthat any particular order be inferred. In addition, as used herein, thearticle “a” is intended to include one or more component or element, andis not intended to be construed as meaning only one. As used herein,“rigidly coupled” refers to two components being coupled in a mannersuch that the components move together in a fixed positionalrelationship when acted upon by a force.

Various embodiments of the invention relate to any combination of any ofthe features, and any such combination of features may be claimed inthis or future applications. Any of the features, elements or componentsof any of the exemplary embodiments discussed above may be utilizedalone or in combination with any of the features, elements or componentsof any of the other embodiments discussed above.

What is claimed is:
 1. A tape measure comprising: a housing; a tape reelrotatably mounted within the housing; a rotational axis defined by thetape reel around which the tape reel rotates; an elongate tape bladewound around the tape reel; a spiral spring coupled to the tape reel,wherein when the elongate tape blade is unwound from the tape reel toextend from the housing the spiral spring stores energy, wherein thespiral spring releasing energy drives rewinding of the elongate tapeblade on to the tape reel, and wherein the spiral spring is made of afirst material that is electrically-conductive; a detector made of asecond material that is electrically-conductive; and a sensor thatmeasures a capacitance of the detector.
 2. The tape measure of claim 1,wherein the sensor generates a first signal as a result of measuring thecapacitance of the detector, wherein the first signal indicates aconfiguration of the spiral spring.
 3. The tape measure of claim 1,wherein the detector is a first detector and the sensor performs a firstmeasurement of the capacitance of the first detector, the tape measurefurther comprising a second detector, the sensor performs a secondmeasurement of the capacitance of the second detector.
 4. The tapemeasure of claim 3, wherein the sensor generates a first signal based onthe first measurement of the capacitance of the first detector and thesecond measurement of the capacitance of the second detector, whereinthe first signal indicates a configuration of the spiral spring.
 5. Thetape measure of claim 3, wherein the first detector circumferentiallyextends around the rotational axis and the second detectorcircumferentially extends around the rotational axis.
 6. The tapemeasure of claim 1, wherein the detector is a first detector and thesensor performs a first measurement of the capacitance of the firstdetector, the tape measure further comprising a second detector and athird detector, the sensor performs a second measurement of acapacitance of the second detector and a third measurement of acapacitance of the third detector, and wherein the first detector, thesecond detector, and the third detector are concentrically arrangedaround the rotational axis.
 7. The tape measure of claim 1, wherein thedetector is a first detector and the sensor performs a first measurementof the capacitance of the first detector, the tape measure furthercomprising a second detector, the sensor performs a second measurementof a capacitance of the second detector, wherein the sensor generates asignal based on a comparison of the first measurement and the secondmeasurement.
 8. The tape measure of claim 1, the tape measure furthercomprises a motor that adjusts an amount of tension in the spiral springin response to receiving the first signal.
 9. A tape measure comprising:a housing; a tape reel rotatably mounted within the housing; arotational axis defined by the tape reel around which the tape reelrotates; an elongate tape blade wound around the tape reel; a spiralspring located within the housing, wherein when the elongate tape bladeis unwound from the tape reel to extend from the housing the spiralspring stores energy, wherein the spiral spring releasing energy drivesrewinding of the elongate tape blade on to the tape reel, and whereinthe spiral spring is made of a first material that iselectrically-conductive; a magnet that emits a magnetic field; and adetector that measures a change in the magnetic field caused by arepositioning of the spiral spring in response to a portion of the tapeblade being extended from or retrieved into the housing.
 10. The tapemeasure of claim 9, wherein the detector generates a first signal as aresult of measuring the change in the magnetic field, and wherein thefirst signal indicates a configuration of the spiral spring.
 11. Thetape measure of claim 9, wherein the magnet is a first magnet and thedetector is a first detector, the tape measure comprising: a pluralityof magnets including the first magnet; and a plurality of detectorincluding the first detector, each of the plurality of detectormeasuring one or more changes to one or more magnetic fields emitted bythe plurality of magnets.
 12. The tape measure of claim 11, wherein theplurality of magnets are arranged at a plurality of radii with respectto the rotational axis.
 13. The tape measure of claim 11, wherein theplurality of detectors are arranged at a plurality of radii with respectto the rotational axis.
 14. The tape measure of claim 11, wherein eachof the plurality of detectors are arranged proximate one of theplurality of magnets.
 15. A tape measure comprising: a housing definingan interior surface; a tape reel rotatably mounted within the housing; arotational axis defined by the tape reel around which the tape reelrotates; an elongate tape blade wound around the tape reel; a spiralspring located within the housing, wherein when the elongate tape bladeis unwound from the tape reel to extend from the housing the spiralspring stores energy, wherein the spiral spring releasing energy drivesrewinding of the elongate tape blade on to the tape reel; an axlerotatably mounted within the housing, the axle defining a first end andan opposing second end; a motor shaft rotatably mounted within thehousing, the motor shaft defining a first end and an opposing secondend, wherein the first end of the motor shaft interfaces with the firstend of the axle; and a sensor that measures a position of the second endof the motor shaft.
 16. The tape measure of claim 15, furthercomprising: a length defined between the second end of the motor shaftand the interior surface of the housing; wherein the sensor measures theposition of the second end of the motor shaft by measuring the length.17. The tape measure of claim 15, wherein the length varies as a resultof the interface between the first end of the motor shaft and the firstend of the axle.
 18. The tape measure of claim 15, further comprising aspring that extends between the second end of the motor shaft and theinterior surface of the housing, wherein the spring exerts a biasingforce on the motor shaft that pushes it towards the axle.
 19. The tapemeasure of claim 15, wherein the sensor generates a first signal as aresult of measuring the position of the second end of the motor shaft,wherein the first signal indicates a configuration of the spiral spring.20. The tape measure of claim 19, the tape measure further comprises amotor that adjusts an amount of tension in the spiral spring in responseto receiving the first signal.